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Lysosomes: Digestive Compartments A lysosome is a membranous sac of hydrolytic enzymes that can digest macromolecules Lysosomal enzymes can hydrolyze proteins,

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Presentation on theme: "Lysosomes: Digestive Compartments A lysosome is a membranous sac of hydrolytic enzymes that can digest macromolecules Lysosomal enzymes can hydrolyze proteins,"— Presentation transcript:

1 Lysosomes: Digestive Compartments A lysosome is a membranous sac of hydrolytic enzymes that can digest macromolecules Lysosomal enzymes can hydrolyze proteins, fats, polysaccharides, and nucleic acids Animation: Lysosome Formation Animation: Lysosome Formation Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

2 Some types of cell can engulf another cell by phagocytosis; this forms a food vacuole A lysosome fuses with the food vacuole and digests the molecules Lysosomes also use enzymes to recycle the cell’s own organelles and macromolecules, a process called autophagy Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

3 Fig. 6-14 Nucleus 1 µm Lysosome Digestive enzymes Lysosome Plasma membrane Food vacuole (a) Phagocytosis Digestion (b) Autophagy Peroxisome Vesicle Lysosome Mitochondrion Peroxisome fragment Mitochondrion fragment Vesicle containing two damaged organelles 1 µm Digestion

4 Fig. 6-14a Nucleus 1 µm Lysosome Digestive enzymes Plasma membrane Food vacuole Digestion (a) Phagocytosis

5 Fig. 6-14b Vesicle containing two damaged organelles Mitochondrion fragment Peroxisome fragment Peroxisome Lysosome Digestion Mitochondrion Vesicle (b) Autophagy 1 µm

6 The Endomembrane System: A Review The endomembrane system is a complex and dynamic player in the cell’s compartmental organization Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

7 Fig. 6-16-1 Smooth ER Nucleus Rough ER Plasma membrane

8 Fig. 6-16-2 Smooth ER Nucleus Rough ER Plasma membrane cis Golgi trans Golgi

9 Fig. 6-16-3 Smooth ER Nucleus Rough ER Plasma membrane cis Golgi trans Golgi

10 Mitochondria and chloroplasts –Are not part of the endomembrane system –Have a double membrane –Have proteins made by free ribosomes –Contain their own DNA Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

11 Mitochondria: Chemical Energy Conversion Mitochondria are in nearly all eukaryotic cells They have a smooth outer membrane and an inner membrane folded into cristae The inner membrane creates two compartments: intermembrane space and mitochondrial matrix Some metabolic steps of cellular respiration are catalyzed in the mitochondrial matrix Cristae present a large surface area for enzymes that synthesize ATP Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

12 Fig. 6-17 Free ribosomes in the mitochondrial matrix Intermembrane space Outer membrane Inner membrane Cristae Matrix 0.1 µm

13 Chloroplasts: Capture of Light Energy The chloroplast is a member of a family of organelles called plastids Chloroplasts contain the green pigment chlorophyll, as well as enzymes and other molecules that function in photosynthesis Chloroplasts are found in leaves and other green organs of plants and in algae Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

14 Chloroplast structure includes: –Thylakoids, membranous sacs, stacked to form a granum –Stroma, the internal fluid Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

15 Fig. 6-18 Ribosomes Thylakoid Stroma Granum Inner and outer membranes 1 µm

16 Overview: Life at the Edge The plasma membrane is the boundary that separates the living cell from its surroundings The plasma membrane exhibits selective permeability, allowing some substances to cross it more easily than others Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

17 Cellular membranes are fluid mosaics of lipids and proteins Phospholipids are the most abundant lipid in the plasma membrane Phospholipids are amphipathic molecules, containing hydrophobic and hydrophilic regions The fluid mosaic model states that a membrane is a fluid structure with a “mosaic” of various proteins embedded in it Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

18 Fig. 7-2 Hydrophilic head WATER Hydrophobic tail WATER

19 Fig. 7-3 Phospholipid bilayer Hydrophobic regions of protein Hydrophilic regions of protein

20 Fig. 7-7 Fibers of extracellular matrix (ECM) Glyco- protein Microfilaments of cytoskeleton Cholesterol Peripheral proteins Integral protein CYTOPLASMIC SIDE OF MEMBRANE Glycolipid EXTRACELLULAR SIDE OF MEMBRANE Carbohydrate

21 Discussion Questions A Panoramic View of the Cell Distinguish between prokaryotic and eukaryotic cells. Explain why there are both upper and lower limits to cell size. Explain the advantages of compartmentalization in eukaryotic cells.

22 Chapter Review Unicellular Multicellular Levels of Organization Metabolisms Organelles Eukaryotes Prokaryotes Ribosomes Endoplasmic Reticulum Golgi Bodies Mitochondria Nucleus Vacuoles Centrioles Plastids Chloroplasts Chlorophyll Lysosomes Cilia Flagella Symbiotic Theory Inside of every cell there is some type of organization that allows cells to perform it’s life functions. Some cells are more complicated that others. In this assignment you will need to explain: 1.a. the process by which a cell takes mRNA (a code for an enzyme) from the nucleus. b. converts it to an enzyme. c. and transports it outside the cell. 2.a. the process by which Starch is taken into the cell. b. Broken down (digested). c. What organelle is it taken to and Why? 3.a. What is the difference between Eukaryotes and Prokaryotes. b. In what type of cell would you find Plastids, Vacuoles and what’s their function. c. In what type of cells would you find Cilia and Flagella and what’s their function.

23 Vacuoles? Fluid filled, membrane bound structures for storage.

24 Cytoskeleton? Gives support and shape to the cell. 2 Parts 1. Microfilaments = protein strands (actin & myosin) - Contractile proteins – support and help in cell movement. 2. Microtubules = long thick proteins that stretch form the cell membrane to the nucleus. Help organelles move with in the cell

25 Centrioles – Cilia / Flagella Centrioles = used in cell division (made of microtubules) Cilia and Flagella – microtubules surrounded by the cell membrane extending outside the cell used for locomotion Play

26 Evolution of Eukaryotes Symbiotic Theory? Prokaryotic Characteristics? Mitochondria and Chloroplasts? Ribosomes? It’s Logical but incomplete. Why? -Nuclear Membrane? -Various Membrane bound structures? -And other eukaryotic structures? Contain their own DNA, RNA and ribosomes that are similar to Prokaryotes. Symbiosis?2 organisms living in close association. DNA = single, double stranded, circular chromosomes No membrane bound organelles, but do have ribosomes (smaller) No Nucleus Smaller in Prokaryotes yet similar enzymes for making proteins and Nucleic Acids

27 Symbiotic Theory


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